Implantable electrode for nerve stimulation



IMPLANTABLE ELECTRODE FOR NERVE STIMULATION 1969} s. 1. SCHWARTZ ET ALSheet of 2 Filed Dec. 10,

INVENTOR. 55.01001: 2'. SCb'k/Jlfz Roazzr c'. MIA/GROVE BY JIMEJ A.400E250 Jan. 14, 1969 5 1, SCHWARTZ ET AL 3,421,511

IMPLANTABLE ELECTRODE FOR NERVE STIMULATION Filed DecL Sheet 5 of 2 /2 7INVENIORS 55:41am? .2: SCHWARTZ ROBERT c. MIA/020V: BY Jone-s A.mvosksou United States Patent 2 Claims ABSTRACT OF THE DISCLOSUREElectrode apparatus for connection to a nerve, having a pair ofelectrodes partially embedded within a substance inert to body fluidsand tissue, the exposed portions of the electrodes lying in a groovegenerally conformed to the shape of the nerve for providing atraumaticegress of the nerve to the electrode, and including a further connectedportion of the material inert to body food and tissue for covering thegroove after the electrodes have been connected to space points on thenerve. Coiled leads are connected to the nerve, and are also encased inmaterial inert to body foods and tissue.

This invention relates to medical apparatus, and more particularly to animplantable electrode for electrical stimulation of a single nervewithin the body of an animal. The word animal is here used in its broadsense, including Homo sapiens.

Briefly described, the apparatus of this invention comprises a pair ofelectrodes almost entirely embedded within a substance, such as siliconrubber, which is inert to body fluids and tissue, and is thus suitablefor implantation in the body of an animal. A pair of flexible leads areconnected to the electrodes and may be used to connect the electrodes toan implanted or external source of electrical signal energy. The leadsare also embedded in a substance which acts as an electrical insulatoras well as being inert to body fluids and tissue. An exposed portion ofeach of the electrodes is formed to be connected to spaced points alonga single nerve, to provide electrical stimulation of the nerve from thesource of signal energy. The electrodes and the leads are also made of amaterial inert to body fluids and tissue; such as platinum or stainlesssteel. An extra member of the substance is provided, such as a flap, fortying down over the electrodes after they have been connected to thenerve.

The need for the apparatus of this invention is apparent uponconsideration of such modern medical equipment as the carotid sinusnerve stimulator fully described in a co-pending application by SeymourI. Schwartz and Robert C. Wingrove, Ser. No. 397,899, entitledImplantable Stimulator for Reducing Blood Pressure in HypertensivePersons. In this co-pending application there is described the use of animplantable, artificial nerve stimulator, which provides electricalimpulses for stimulation of the carotid sinus nerve to alleviate theproblems of hypertensive animals.

Electrical impulses for major organs of the body of an animal may betransmitted to that organ by means of pointed electrodes which penetratethe body of the organ and indirectly make contact with a nerve networkwithout damaging the organ. Such general stimulation is not etfectivewhere the impulse must be superimposed on one particular nerve and thatnerve alone. The present structure is designed to allow transmission ofan electrical impulse specifically and solely to a selected nerve, suchas the carotid sinus nerve or the vagus nerve, by way of example.

In the drawings,

FIG. 1 is a view of a first embodiment of the invention as may be usedwith an implantable source of electrical signal energy;

FIG. 2 is a sectional view of FIG. 1 taken along the line 2-2 andshowing a hinged flap which may be fastened over a nerve connected tothe electrodes;

FIG. 3 is a sectional view of FIG. 2 taken along the line 3-3;

FIG. 4 is a plan view of the first embodiment of this invention showingthe flap fastened over the electrodes connected to a nerve;

FIG. 5 is a sectional view of FIG. 4 taken along the line 55;

FIG. 6 is a view of a second embodiment of this invention also connectedto the implantable source of electrical signal energy;

FIG. 7 is a sectional side view of the second embodiment of thisinvention showing the head of the second embodiment having a slotforming an upper and lower layer;

FIG. 8 is a sectional view of FIG. 7 taken along the line 8-8;

FIG. 9 is a perspective view of the second embodiment of this invention;and

FIG. 10 is a sectional view of the drawing of FIG. 6 taken along theline 10-10.

FIG. 1 discloses a first embodiment of this invention having a headindicated generally at 12, including an electrode carrying member 13 anda flap member 15. A lead carrying member or tail 14 is connected to head12. Tail 14 is also shown connected to an implantable source ofelectrical signal energy 11.

FIG. 2 is a side view of head 12 showing a groove 20 in member 13, andshowing flap 15 folded over and connected to member 13.

FIG. 3 discloses a pair of electrodes 22 and 24 partially encapsulatedin member 13 and formed into the groove 20. A pair of leads 26 and 28,here shown as coiled lengths of an electrically conductive material, areconnected, respectively, to electrodes 22 and 24. Leads 26 and 28 arealso encapsulated in the substance of tail 14.

FIG. 4 discloses electrodes 22 and 24 connected to spaced points along anerve 27 in groove 20. Flap 15 is shown folded over to cover and thusinsulate electrodes 22 and 24 and nerve 27 in groove 20. Flap 15 isfastened to member 13 by use of sutures 29.

FIG. 5 also discloses the nerve 27 as covered over by the flap 15fastened to member 13 by sutures 29.

FIG. 6 discloses a second embodiment of this invention having a headindicated generally at 112, a tail 114 connected to head 112 and alsoconnected to a source of electrical signal energy 111.

FIG. 7 is a side view of head 112 disclosing a slot 121 out in head 112to form an upper layer 115 and a lower layer 113. A groove is shown inlower layer 113.

FIG. 8 discloses a pair of electrodes 122 and 124 partially encapsulatedin the substance of lower layer 113, and partially formed to groove 120.A pair of leads 126 and 128, here shown as coiled lengths of anelectrically conductive material, are connected, respectively, toelectrodes 122 and 124. Leads 126 and 128 are encapsulated in thesubstance of tail 114.

FIG. 9 is a perspective view which discloses electrodes 122 and 124connected to spaced points along the length of a nerve 127.

FIG. 10 again shows nerve 127 within the groove 120 with upper layer 115fastened to lower layer 113 by sutures 129.

Since this invention comprises electrodes which are to be implantedwithin the body of an animal, it is necessary that the substance whichcomprises head 12 and 112 and .9 tail 14 and 114, be inert to bodyfluids and tissue. Such a substance which has been successfully used issilicon rub'ber. It is also necessary that electrodes 22 and 24, and 112and 124, which must connect directly to the outer wall of a nerve 27 or127, be of a material inert to body fluids and tissue and be not harmfulto the outer wall of the nerve to which they are attached. Such amaterial which has been successfully used is platinum. Another materialwhich may also be used is stainless steel. Leads 26 and 28, and 126 and128 must also be of a material inert to body fluids and tissue. It maybe desirable, but is not mandatory that leads 26 and 28, and 126 and128, be of the same material as electrodes 22 and 24, and 122 and 124.

The leads in the embodiments here shown are disclosed as being coiledlengths of a material, to facilitate ease of flexibility. This hasproven to be a highly desirable type of lead structure, but it is notintended that this entire invention be limited to such a lead structure.

While it is necessary that a portion of electrodes 22 and 24, and 122and 124, not be encapsulated in the substance of head 12 so that theelectrodes may be connected to nerve 27 or 127, it is highly undesirableto leave the electrodes exposed after connection to the nerve. Toovercome this problem the embodiments of this invention provide either aflap 15 or an upper layer 115. As shown in FIGS. 4 and 5, flap 15 may befolded over to cover electrodes 22 and 24 when they are connected tonerve 27. Flap 15 is then fastened to member 13, such as by sutures 29.As shown in FIGS. 7, 9 and 10, upper layer 115 is separated from lowerlayer 113 only by the width of slot 121. When electrodes 122 and 124have been connected to nerve 127, upper layer 115 may be fastened downupon them by means such as sutures 29.

Groove 20 in member 13, and groove 120 in lower layer 113, are shapedgenerally to the configuration of nerves 27 and 127, respectively, andalso facilitate firm fastening and insulation of the connection of theelectrodes to the nerves.

The sources of electrical signal energy 11 and 111, shown in FIGS. 1 and6, respectively, may be transistorized blocking oscillators powered bylong life rechangeable batteries, which provide pulses at apredetermined frequency to the nerves 27 and 127, respectively. Thoughthe sources 11 and 111 shown here are implantable, that is, areencapsulated in a substance inert to body fluids and tissue forimplantation in the body of an animal, it is not mandatory that theelectrode apparatus of this invention be used with an implantable sourceof electrical signal energy. The tails 14 and 114, including leads 26and 28, and 126 and 128, respectively, may extend from within the bodyto a point external to the body, and be connected to any one of a numberof sources of electrical signal energy. Also, the leads may extend to acircuit implanted in the body but powered from a source external to thebody.

The electrode apparatus of this invention has been successfullyimplanted in a human being, and shown to be fully operable in providingelectrical impulse stimulation to a carotid sinus nerve in one case andto a vagus nerve in a second case. In the various embodimentssuccessfully used, silicon rubber was used as the substance toencapsulate the leads and electrodes. In at least one such embodimentthe electrodes were made of platinum, while the leads were made ofcoiled lengths of stainless steel.

It is apparent from the foregoing description that the apparatus of thisinvention provides a noved structure for connection of a source ofsignal energy to a single nerve, to provide artificial stimulation ofthat nerve by timed electrical impulses from the source of signalenergy. Further, the apparatus of this invention has been used and hasbeen successful in alleviating medical problems of human beings.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. Electrode apparatus implantable in the body of an animal forstimulation of a single nerve comprising:

a housing of an electrically insulating substance substantially inert tobody fluids and tissue, said housing having a head and a tail extendingtherefrom;

a slot in said head dividing a part of said head into an upper layer anda lower layer;

a groove in said lower layer adjacent said slot;

a pair of electrodes of an electrically conductive materialsubstantially inert to body fluids and tissue, and encased in said headof said housing in spaced relation to one another;

a portion of each of said pair of electrodes formed to and fitted insaid groove, said portions adapted to be connected to spaced points on asingle nerve in the body of an animal;

said upper layer of said housing adapted to be fastened to said lowerlayer to hold and shield the single nerve in contact with said pair ofelectrodes;

a pair of leads of said material encased in said tail of said housing;and

each of said pair of leads connected to a-ditferent one of said pair ofelectrodes, for connecting said pair of electrodes to a source of signalenergy for stimulating the single nerve.

2. Medical apparatus for implantation into the body of an animalcomprising:

first and second electrodes of an electrically conductive materialsubstantially inert to body fluids and tissue;

first and second leads of said material connected, re-

spectively, to said first and second electrodes, and adapted to beconnected to a source of electrical signal energy;

a first portion of said first and second electrodes and said first andsecond leads being encapsulated in a housing of an electricallyinsulating substance substantially inert to body fluids and tissue;

a second portion of said first and second electrodes adapted to beconnected to spaced points along a single nerve in the body of ananimal, for stimulation of the single nerve upon receipt of a signalfrom the source of signal energy; and

a further member of said substance flexibly connected to said housingfor fastening over said second portion of said first and secondelectrodes when connected to the single nerve.

References Cited UNITED STATES PATENTS 3,157,181 11/1964 McCarty 128-4043,216,424 11/1965 Chardack 128418 WILLIAM E. KAMM, Primary Examiner.

